THERMO-ELECTRICITY

When one part of a metallic bar is heated and another cooled, an electric current is generated in its substance, which may be rendered evident and it3 direction ascertained by the galvanometer. When two metals of different temperatures are brought into contact similar electric currents are generated, the quantity and direction of the electricity varying with tha nature of the metals and their respective temperatures. The best apparatus for exhibiting these thermo-electric currents consists of alternate bars of antimony and bismuth soldered together at their ends, so as to form a compound bar or parallelogram, the junctions of which may be alternately heated and cooled: in this case the direction of the current is from the antimony to the bismuth; so that these metals bear the same relation to each other in the thermoelectric series, as the zinc and silver in the simple voltaic circuit. The term stereo-electric has also been applied to these currents, implying their production in solid bodies independent of a fluid, and as opposed to the hydro-electric or voltaic current. See Voltaic Battery. [s. 1252]